Problem of the Week #151: September 9


Cash game, Black owns the cube.




Black to play 5-1.



Note: All ‘cash game’ problems assume the Jacoby Rule is in effect. That is, you can’t win a gammon unless the cube has been turned.

I like 24/23 for the 1 then 8/3. Saves a few gammoms and double 4s brings hope

This position is beyond repair. Three man back vs. 2 facing a 5 prime with active spares. Having killed a checker on ace with a semi dead on five. The only thing we can do is creating an accident on the way to the bank for white. Playing pure, 44 isn't really a harm. The men from white will stay in play, the position is to repair. But if you hold the block on eight, look at the white position after 66. Suddenly a dilly builder on two. The front position looks brittle. One captured man can get out with 5 and 6. And the dead man from black is into life as a part of a closed door.

I will create the better root number.

23/22 6/1.

Black has one big concern, and that is to get off the gammon. The best way in that case is 6/5 6/1.

Tough one. If I break the 8-pt, I have to leave a direct shot. If I break the 6-pt, I can then secure the blot with 6/5, but I then fail to advance to the edge of his prime. Let's do a more thorough analysis:

1) 8/3 8/7 : 6s escape, 5s escape and hit, 4s and 3s could hit loose
2) 8/3 23/22: 6s escape and hit, 5s escape or hit loose on the edge, 3s and 2s hit loose on the edge
3) 8/3 24/23: 6s escape and hit, 5s escape
4) 6/1 6/5 : 6s hit loose, 5s escape, 4s escape, 3s could hit loose
5) 6/1 23/22: 5s escape or hit loose on the edge, 4s escape and hit, 3s and 2s hit loose on the edge
6) 6/1 24/23: 6s are frozen, 5s escape, 4s escape and hit

Moving to the edge is important to regain some timing, but it's dangerous and it doesn't guarantee we'll get a 6 soon after that. Situation looks so desperate, is it time to cut the losses and reduce the gammon rate?

I think I go with the "delay" move and play 6/1 6/5.

6/1 6/5

Best solution is to see if your opponent is dumb enough to take a 2pt resignation. :-)

Seriously, the best thing you can do is give your opponent bad numbers. You only have two legal fives so not a lot of choices there. Conventional wisdom says break from the back but in this case that looks terrible so 6/1 is our five.

Only two reasonable 1's to play, slot the edge of the prime or make the 23pt anchor. Slotting the edge of the prime is also conventional wisdom in a lot of situations but if you do that some of the 6's that would crack white's prime will play fine. If you block 6's from the end of the prime with the anchor then the 6's that don't run will crack his prime.

24/23 6/1

You're right Nick, 6s aren't frozen after your move, he can play 7/1* to his ace point.

+1

Not only is your situation garbage on inspection with 3 men stuck well behind a 5-prime, but if you play a couple more rolls without something major happening, you've crunched as well. He can play all the little numbers with his spares anyway, 5s run, so I don't see much else besides trying to make his 6s suck, and this makes them uglier than 23/22. Hope he rolls one and then hope for the best.

23/22 8/3


As from today I will try to keep a record of the percentage of right answers.
ps: I suck at BG

0/0

How did you get your status of adept by the way.

If you're referring to me, I honestly don't know.
I believe it's the standard ranking, say from 500 to 1k posts?... I really don't know.

Ouch. Played to quick. Your ace is a monster. Forgot the rule of thumb to look which formation sucks which numbers.

Sorry that i forgot to place a smiley.

Black is in a nearly hopeless situation. In most variations, he will crash completely before he extricates his three back checkers.

Given this, I think it is important to advance the anchor with the 1. Losing a gammon in a 2pt holding game is about half as likely as from the 1pt, roughly 7-8% overall.

That done, Black can begin to think of ways to maximize his small chances of actually winning this game. In order to forestall cracking, Black needs to escape at least one checker immediately. He should be thinking of the numbers that might force White to break his block, especially 6s. If Black abandons the 8pt, White can hold his block while playing almost any roll. With the 8pt blocked, and the anchor on the 2pt, many of White’s 6s must be played by breaking his bar point. If Black makes the unorthodox move of breaking his 6pt, then White will crack on 5 rolls: 62, 63, 66 (plus a few awkward doublets).

The only problem with this plan is that Black also increases the number of his gammon losses whenever he has another checker sent back. Being hit on the 6pt carries a very real cost. So, if this is not correct, my second pick would be to keep the 24pt, and lift the 6pt completely. But that would be a give-up play.

My solution: 24/23, 6/1

For the Record
I am so often wrong that I like to post my record in these messages. It's kind of a truth-in-advertising thing. Grunch: I have been answering these problems without the use of a bot, and before checking the excellent solutions of others, since Problem 28. My record at this writing is 54%.